1. Technical Field
This invention relates to the technology of cleansing environmental air of noxious gaseous elements, and more particularly to techniques for removing such elements from the passenger compartment of an automobile with equipment carried on-board such vehicle.
2. Discussion of the Prior Art
Oxidants, which may include ozone, nitrogen dioxide, peroxy nitrates (such as PAN), can have long-term injurious effects on occupants of a vehicle. U.S. Pat. No. 4,184,983 describes the desirability of eliminating ozone from the atmosphere in general by certain techniques used to the date of the patent (1978). Recently, it has been appreciated that the problem of oxidant concentration may be increased inside automobiles when traveling on congested roads at speeds of less than 25 mph.
Prior art techniques for cleansing noxious emissions from the exhaust of engines or combustion processes of plants have progressed from using noncatalytic absorbants to the use of catalytic materials that chemically decompose or reduce such oxidants to nonpollutants. The use of noncatalytic absorbents is represented in U.S. Pat. No. 3,870,495 (1972) wherein random woven fibers carrying charcoal are used to cleanse the air intake of an interior compartment of a vehicle. In U.S. Pat. No. 4,184,983 (1980), a catalytic metal or metal oxide comprised of platinum, palladium, ruthenium, rhodium, osmium, or iridium is supported on refractory inorganic oxides such as alumina. The use of catalytic materials for chemical decomposition have included: U.S. Pat. No. 2,298,607 (1942), using precious metal or metal oxides on a glass wool support; U.S. Pat. No. 4,184,983, which uses a catalytic metal or metal oxide comprised of one or more of platinum, palladium, ruthenium, rhodium, osmium, iridium, supported on a refractory inorganic oxide such as alumina; PCT International Application WO85 01,704 (Oct. 11, 1983), to H. Heinz et al, describing removal of toxic pollutants entering a motor vehicle compartment by use of chemisorption filters which have catalytic materials thereon but which require preheating of air to be treated before contact by the catalyst; UK Patent Application GB 2,122,103 (Jan. 11, 1984), to M. Yamamoto et al (Toyota Central Research and Development Laboratories), describing purifying air for passengers in automobiles by simultaneous oxygen enrichment along with the use of a filter carrying films of plasma polymer of hexamethyldisiloxane to remove nitrogen and particulate pollutants; and German Offen. DE 3,740,091 (Jun. 15, 1989), describing a zig-zag shaped filter carrying catalytic material on a thermoplastic body to transform pollutants in the intake air to harmless substances.
To eliminate the need for replacement of absorbents which are consumed in the cleansing process of intake air to vehicles, U.S. Pat. No. 3,616,339 proposed the use of an electrochemical apparatus to selectively oxidize contaminants, such as ketones, butanol, toluene, etc., by the use of an ion exchange electrolyte supported on glass fibers, paper or polymeric material and by the use of electrodes, the positive electrode being comprised of lead oxide, bismuth, or antimony, and the negative electrode being comprised of graphite or precious metal such as palladium, rhodium, or platinum. The apparatus did not require any positive movement of air and gave no indication of the voltage that was required for operating the electrolytic cell.
It is a goal of this invention to selectively remove oxidants by reduction from the fresh air intake of a ground transport motor vehicle and to do so by use of an electrolytically generated reducing condition at the negative electrode that permits reduction of the undesirable oxidants. Such process and apparatus need not require heating of the air nor does it significantly remove desirable gases such as oxygen.